Protein for Muscle, Resistance Training and Recovery: Timing and Distribution

What trials and sports-nutrition groups report about protein for muscle, resistance training and recovery: total daily intake, who gains most, and the safety points to know.

Content last updated October 22, 2026. This page has not been medically reviewed.

Quick answer

Muscle responds to training, and protein supplies the building blocks. The British Heart Foundation (BHF, a UK charity) puts it this way: to build muscle you need to exercise, particularly strength exercises, and eat enough protein. [1] In trials, extra protein on top of resistance training gives a small extra gain, not a large one. [2][3] This page reports research findings and group positions with their population and source. They are not a personal prescription. How the day is spread across meals is covered on Protein Timing, Meal Distribution and the Anabolic Window; sport-specific positions are on Protein for Endurance, Strength and Team-Sport Athletes.

Evidence labels: evidence in adequately nourished people (trials in healthy people), mixed, and insufficient evidence.

What the trials found

Question	What the source found	Evidence label
Does extra protein add to resistance training?	49 randomized trials (1,863 healthy adults, training at least 6 weeks): small gains in fat-free mass (0.30 kg on average), strength and muscle size. [2]	Evidence in adequately nourished people; small effect
Who gains most?	The effect on fat-free mass shrank with increasing age and was larger in resistance-trained people. [2]	Evidence in adequately nourished people
Is there a ceiling?	Beyond total intakes of about 1.62 g per kg of body weight a day, supplementing gave no further fat-free mass gain. [2]	Evidence in adequately nourished people
Do other reviews agree?	A review of 74 trials in healthy, non-obese adults found small gains in lean mass and lower-body strength; the effect on handgrip strength was unclear. [3]	Evidence in adequately nourished people; small effect
Does the protein source matter?	A network meta-analysis of 116 trials found milk proteins, red meat and mixed protein effective for gains in muscle mass and strength. [4]	Evidence in adequately nourished people

Most trials in these reviews tested extra protein during resistance training. [3] They do not show what extra protein does without training. One author of the 74-trial review discloses honoraria from a US dairy body. [5]

What groups report about amounts

Study findings and position statements are not the same as official requirements. Each row is the published level for the stated group, not advice for you.

Source	Group	Level reported
Health Canada, 2025 page (values from the 2005 US and Canadian reference intakes)	Adults 19 and over	RDA 0.80 g per kg of body weight a day, the general-population level [6]
BHF (UK), 2026	Regular intense strength training, or endurance athletes	Around 1.2 to 2 g per kg a day [1]
BHF (UK), 2026	Vigorous activity such as regular running or heavier workouts	Around 0.75 to 1.2 g per kg a day [1]
International Society of Sports Nutrition (ISSN), 2017	Healthy exercising individuals	1.4 to 2.0 g per kg a day is sufficient for most [7]
ISSN, 2017	Resistance-trained people in periods of eating fewer calories	2.3 to 3.1 g per kg a day may be needed to maximize retention of lean mass [7]
Synopsis of a Canadian Nutrition Society conference (Phillips and colleagues), 2016	Adults	At least 1.2 to 1.6 g per kg a day of high-quality protein described as a more ideal target [8]

The groups differ, and the highest figures are positions, not proof that more is better: the meta-analysis above found no further fat-free mass gain past about 1.6 g per kg. [2] The ISSN authors include people who disclose ties to companies selling protein supplements. [9]

Recovery

The ISSN says an acute bout of exercise and protein ingestion both stimulate muscle protein synthesis. [7] For endurance athletes it says carbohydrate comes first and that adding protein may help offset muscle damage and promote recovery. [7] That is a group position; for detail on endurance see the athletes page above.

For recovery after resistance exercise, a meta-analysis (29 studies in the review, 40 trials in at least one analysis) found that protein around exercise helped preserve maximal strength at several time points and lowered a blood marker of muscle damage (creatine kinase), but had no effect on muscle soreness compared with a control. [10] Authors noted conflicting data, possibly from differences in methods. [10] Strength measured days later is a more useful outcome than a blood marker, but these were short studies. A 2025 systematic review of plant proteins after resistance exercise in healthy young adults (24 studies) judged the evidence limited by small samples and a moderate to high risk of bias, and did not run a meta-analysis. [11] Evidence label: mixed.

Age and diet pattern

The gain from supplementing was smaller with increasing age in the 49-trial analysis. [2] Older adults are covered in Protein for Older Adults and Vegetarian or Vegan Diets and the Wellness page Strength Training and Protein for Older Adults.

Frequently asked questions

How much protein builds muscle?

Groups report different ranges. The ISSN says 1.4 to 2.0 g per kg a day is sufficient for most exercising people, and the BHF gives around 1.2 to 2 g for intense strength training. [7][1] A dietitian can work out a figure for a specific person.

Is more protein always better for muscle?

No. In one analysis, supplementing gave no further fat-free mass gain beyond about 1.62 g per kg of total daily intake. [2]

Do I need to train for extra protein to work?

Most trials tested extra protein during resistance training, so the evidence is about that situation. [3] The BHF also says muscle needs exercise as well as protein. [1]

Is there an anabolic window right after a workout?

See Protein Timing, Meal Distribution and the Anabolic Window. A meta-analysis found total protein intake the strongest predictor of hypertrophy, not timing. [14]

Is a high-protein diet bad for the kidneys?

Sources differ. The BHF warns about regular intakes above 2 g per kg, particularly with kidney problems, while the authors of a conference synopsis wrote that they found no evidence-based link between higher protein diets and renal disease. [1][8] If you have kidney disease, ask your care team. [12]

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

Safety

Kidneys: the BHF says regularly eating more than 2 g per kg a day can strain the kidneys, especially for people with kidney problems. [1] The authors of a conference synopsis wrote that they could find no evidence-based link between higher protein diets and renal disease. [8] Those two statements differ, and the evidence is mixed. People with chronic kidney disease may need to limit protein and should work with a dietitian or clinician. [12]
Products: supplements may interact with medicines, and many have not been tested in pregnant women, nursing mothers or children. [13] See Medication Interactions, Protein Powder Safety and, for athletes who are drug-tested, Sports Certification and Banned-Substance Contamination.
Children, pregnancy, liver disease: needs differ; see Protein for Children and Teens and Protein Powder During Pregnancy and Breastfeeding.
Before surgery: some supplements may increase bleeding or affect anesthesia, so tell your providers about everything you take. [13]

Do not change a prescribed medicine or a medical diet because of a sports article. Ask a clinician, pharmacist or registered dietitian.

References

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.